Measuring instrument.



P. M. LINCOLN & B. H. SMITH.

MEASURING INSTRUMENT.

APPLICATION men mm. 1911.

Patented Apr. 15,1919.

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P. M. LINCOLN & B. H. SMITH.

MEASURING INSTRUMENT. APPLICATION FILED APRLS 39H.

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ATT.ORNEY Patented Apr. 15, 1919.

P. M. LINCOLN & B. H. SMITH.

MEASURING INSTRUMENT.

APPLICATION FILED APR. 5. 1917.

Patented Apr. 15, 1919.

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: ATTORNEY UNITED STATES PATENT OFFICE.

AND BENJAMIN E. SMITH, OF TURTLE CREEK,

PENNBYLYANIA: SAID SIITH ABBIGNOR TO WESTINGHOUSE ELECTRIC AND HANU- 'IIACTUBINQ COMPANY, A CORPORATION O! PENNSYLVANIA. i

' NELSUBING INSTRUMENT.

Specification of Letters Patent. Patented Apr, 15, 1919.

Application fled April 5, 1011. Serial in. 159,925.

To all whom it may concern:

Be it known that we Pam. M. LINCOLN, a citizen of the United States, and a resident of Pittsburgh in the county of Allegheny and State of Pennsylvania, and BENJAMIN H. SMITH, a citizen of the United States, and a resident of Turtle Creek, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Measuring Instruments, of which the followin is a specification.

i ur invention relates to electrical measuring instruments and particularly to maximum-demand meters.

One object of our invention is to provide a meter of the above indicated character that shall be adapted to slowly respond to the energy to be measured.

Another object of our invention is to provide a slowly-responsive wattmeter of the thermal type that shall have means for ualizing the radiation and dissipation of cat from. its thermal elements.

A further object of our invention is to provide a maximum-demand meter of the above indicated character that shall be simple to construct and accurate and reliable in its operation.

U. S. Patent No. 1,156,412, issued October 12, 1915, to Paul M. Lincoln discloses a slowly responsive wattmeter havin a maximum-demand attachment. This evicc so utilizes the heating effects of the current and the voltage of the circuit thatthe pointer is responsive to the difi'erential eflects of the current and the voltage at pre etermined intervals of time, and, consequently, ,to the power traversing the circuit.

In our present invention, we have utilized the broad principles of the above indicated invention but have simplified the device and provided means for equalizing the heat dissipation from its thermal-responsive members. That is, we provide a rotatable shaft having an indicator at one end, two spiral bimetallic springs surrounding the shaft intermediate its ends and adapted to exert opposing actions thereon windings symmetrically disposed between, and at each side of, the springs for heatin the same in accordance with the sum an the difference of the measured, and means disposed on the other end or the shaft for equalizing the radiation and dlmipation of heat from the springs.

In the accompanying drawings, Figure 1 1s a front new, with parts broken away, of a max mum-demand meter embodying our invention; Fig. 2 is a diagram illustrating the connections of the instrument shown in Fig. 1 Fig. 3 is a side view, partially in elevatlon and partially 'in section, of the instrument shown in F' 1; Fig. 4 is a front elevational view of t e thermal-responsive elements ofrthe meter shown in Figs. 1, 3, and Fig. 5 is a side View, partially in section and partially in elevation, of the thermalresponsive elements shown in Fig. 4, and

Fig. 6 is a view taken in Fig. 5.

The instrument inclosing casing 2 thereof along the line VIVI are supported heating windings 16, 17, 18

and 19. The windings 16, 17, 18 and 19 are adapted to so evenly heat the springs 14 and 15 that the dissipation and radiation of heat caused by the windings is equalized.

The heating windings 16 and 19 are connected in series relation to the winding 20 of the transformer 5, and the windings 17 and 18 are connected in series relation to the winding 21 of the transformer 4. The winding 22 of the transformer 5. is connected in shunt relation to the conductors of one phase of the circuit 23, the power traversing which is to be measured, and the winding 24 of the transformer 4 is connected in shunt relation to the conductors of the other phase of the circuit 23. The parallel-connected circuit between the mid-point 25 of the winding 21 and the mid-point 26 between the windings 17 and 18 is connected in series relation with one conductor of the circuit 23. Similarly, the circuit between the midpoint 27 of the winding 20 and the mid- 18 connected in series relation to another conductor of the circuit 23.

With the above-mentioned connections, the windings 16 and 19 are supplied with current in accordance with the sum and the difference of the current and voltage traversing one phase of the circuit 23, and the windings 17 and 18 are supplied with current in accordance with the sum and the difierence of the current and voltage traversing another phase of the circuit 23. Since the windings 16 and 17 are associated with the spring 14, the latter will be heated in accordance with the square of the sum of the currents and voltages of both phases of the circuit 23, and, since the spring 15 is as sociated with the windings 18 and 19, it will be heated in accordance with the square of the difference of the currents and voltages of both phases of the circuit 23. Consequently, if the springs 14 and 15 are opposed in their action, the resultant of their thermal-responsive effects will be proportional to the power traversing the circuit 23.

The inner ends of the springs 14 and 15 are operatively connected to the shaft 7 and their outer ends are connected to the cylindrical members 12 and 13. However, they are so oppositely disposed with respect to each other that they exert opposing actions upon the shaft 7. The pointer 10 is mounted directly upon the shaft 7 and is provided with a lug or projection 29 that is adapted to engage the pointer 11 for the purpose of moving the same in one direction in accordance with the movement of the pointer 10. The pointer 11 is mounted on a sleeve 30 that loosely surrounds the shaft 7 and upon which is also mounted a ratchet wheel 31. The ratchet wheel 31 is adapted to be en-- gaged by a pawl 32, and a spring 33 is provided for returning the pointer 11 to its initial position when the pawl 32 is disengaged from the ratchet wheel 31. A springrestrained member 34-is provided for moving the pawl 32 out of engagement with the -tively connected to one end of a spring 38 ratchet wheel 31 when it is desired to permit the pointer 11 to be reset.

The shaft 7 is provided with a control sprin 35 one end of which is connected to an a 1ustable member 36 and the other end of which is connected to the shaft 7. Thus, the pointer 10 may return to its initial position when no current traverses the windings 16, 17, 18 and 19. A crank or lever arm 37 is secured to the shaft 7 at a point between the elements 8 and 9 and is operathe other end of which is connected, throu h an adjusting device 39, to the lug 3. T e spring 38 is utilized for the purpose of adjusting the full-load indication of the instrument to cause the instrument to be accurately responsive for all values of .power.

. instrument and thereby causes the differential action of the two elements 8 and 9 to be proportional to the power traversing the circuit 23.

Since the springs 14 and 15 are heated in accordance with the square ofthe sum of the voltage and current traversin the circuit 23 and the square of the di erence of the voltage and currents traversing the circuit 23 and, since the diiferential action of the springs 14 and 15 is transmitted to the shaft 7, it will be readily understood that the pointer 10 will be actuated in accordance with the differential of these two values and, consequently, in accordance with the power traversing the circuit 23. However, the thermal elements 8 and 9 are so insulated and the resistances of the windings 16, 17 18 and 19 are of such values that the pointer 10 requires a definite time to reach the maxi- .mum value of the power to be measured.

sition until manually reset by means of the member 34.

We do not limit ourinvention to the particular structure illustrated, as it may be variousl modified without departing from the spirit and scope of the invention as se forth in the appended claims. 4

We claim as our invention:

1. An electrical measuring instrument comprising a shaft, an indicating member mounted thereon, two thermal-responsive spring members surrounding the shaft to exert opposing actions thereon and means for heating one of the spring members in accordance with the sum, and the other in accordance with the difference, of the voltage and current of the circuit to be measured.

2. A wattmeter for an electric circuit comprising a rotatable member, two thermo- 126 static sprin members surrounding the rotatable mem er and adapted to exert oppos ing actions thereon, and means for heating one. of the spring members in accordance with the sum, and the other in accordance with the difference, of the voltage and current traversing the circuit to be measured.

3. A measuring instrument for an electric circuit comprising an indicating element, two bimetallic spiral spring members adapted to exert opposing actions on the said element, and means for heating one of the spring members in accordance with the sum, and the other in accordance with the difference, of the voltage and current traversing the circuit to be measured.

4. A. measuring instrument for an electric circuit comprising a rotatable shaft, a pointer mounted on one end thereof, a spring for controlling the resetting of the pointer, two thermostatic spring members surrounding the shaft and adapted to exert opposing actions thereon, means for heating the sprin members in accordance with the sum an the difference, res ctively, of the current and voltage traversing the circuit, and means mounted adjacent to the other endof the shaft to compensate for the heat dissipation caused by the pointer and the control spring on the other end of the shaft. 1 v

5. A measuring instrument for an electric circuit comprising a rotatable shaft, a pointer mounted at one end thereof, thermalresponsive means surrounding the shaft intermediate its ends and ada ted to exert 0 posing actions thereon, an means associated with the other end of the shaft to compensate for the unequal heat dissipation caused by the heat conduction of the pointer.

6. A measuring instrument for an electric circuit comprising a rotatable shaft, indicating means mounted at one end thereof, thermal-responsive means surrounding the shaft intermediate its ends and adapted to exert opposing actions thereon, and means mounte at the other end of the shaft to com ensate for the unequal heat dissipation cm the thermal-responsive means caused bythe indicating means.

7. An electrical measurin instrument comprising a rotatable sha indicating means mounted at one end thereof, two thermal-responsive means attached to the shaft intermediate its ends and adapted to exert opposing actions thereon, and means associated with the'other end of the shaft to compensate for the unequal heat dissipation from the two thermal-responsive devlces.

8. An electrical measuring instrument comprising a rotatable shaft, indicating means mounted at one end thereof, two thermal-responsive means attached to the shaft intermediate its ends and ada ted to exert opposing actions thereon, and eat-conducting means mounted at the other end of the shaft to equalize the heat dissipation of the two thermal-responsive means.

9. An electrical instrument comprising an indicating member, two thermal-res onsive spring member's attached to the in icating member, and adapted to exert opposing actions thereonfiand means for equalizing the heat dissipation from the two thermal-responsive members.

10. A slowly-responding wattmeter comprising a rotatable shaft, an indicator mounted thereon, two bimetallic springs surrounding the shaft and adapted to exert opposing actions thereon, and a winding at each side of each spring for heating the same in accordance with the sum and the difference of the current and voltage of the circuit to be measured.

In testimony whereof, we have hereunto subscribed our names this 29th day of March, 1917.

PAUL M. LINCOLN. BENJAMIN H. SMITH. 

